In a gyratory crusher where the crusher head shaft passes through a drive eccentric and is adjustable under load in a vertical direction, clearance must exist between the shaft and the inner race of the inner bearing of the eccentric. Also, due to the fact that the crushing load will rotate or more angularly relative to the shaft in the direction that the drive eccentric rotates, the bearing inner race should be an interference fit on the shaft. If the inner race is not an interference fit, rapid wear will occur on both the shaft and the bearing bore.